The present invention relates to a method and a device for splicing an aged optical silica fiber to another fiber, e.g. to a new optical fiber for repair purposes.
It is well-known that optical fibers based on silica corrodes in a humid environment. Further, substantially all optical fibers which are installed for ordinary telecommunication in national networks are exposed to moisture to a larger or smaller extent. Naturally, the surface of a silica fiber is in particular exposed to corrosion attacks. The attacks cause that the tensile strength of the fiber is reduced and that the fiber gets more brittle. The deterioration of the mechanical characteristics of fibers is a large problem when repairing e.g. a fiber which is installed below ground level and has been cut off in some digging operation. Installed, aged fiber can be so brittle that it may be difficult to handle it and it can even be impossible to splice the fiber to other fibers. Up to now, for failures such as breaks or ruptures of old fibers, it has often been necessary to replace whole fiber lengths which is naturally very costly.
It has been observed previously that the rupture and tensile strength of glass fibers and wave guides can be increased by heating the fibers or waveguides to temperatures in the vicinity of the softening temperature, see the German patent applications made available to the public DE-A1 28 17 651 for Siemens AG and DE-A1 40 41 150 for kabelmetal electro GmhH. The methods and devices disclosed are conceived to be used on ordinary fibers, before the practical use thereof.